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Revision 1.26 by root, Tue Nov 27 19:41:52 2007 UTC vs.
Revision 1.30 by root, Wed Nov 28 11:27:29 2007 UTC

… …
127.\} 127.\}
128.rm #[ #] #H #V #F C 128.rm #[ #] #H #V #F C
129.\" ======================================================================== 129.\" ========================================================================
130.\" 130.\"
131.IX Title ""<STANDARD INPUT>" 1" 131.IX Title ""<STANDARD INPUT>" 1"
132.TH "<STANDARD INPUT>" 1 "2007-11-27" "perl v5.8.8" "User Contributed Perl Documentation" 132.TH "<STANDARD INPUT>" 1 "2007-11-28" "perl v5.8.8" "User Contributed Perl Documentation"
133.SH "NAME" 133.SH "NAME"
134libev \- a high performance full\-featured event loop written in C 134libev \- a high performance full\-featured event loop written in C
135.SH "SYNOPSIS" 135.SH "SYNOPSIS"
136.IX Header "SYNOPSIS" 136.IX Header "SYNOPSIS"
137.Vb 1 137.Vb 1
138\& #include <ev.h> 138\& #include <ev.h>
139.Ve 139.Ve
140.SH "EXAMPLE PROGRAM"
141.IX Header "EXAMPLE PROGRAM"
142.Vb 1
143\& #include <ev.h>
144.Ve
145.PP
146.Vb 2
147\& ev_io stdin_watcher;
148\& ev_timer timeout_watcher;
149.Ve
150.PP
151.Vb 8
152\& /* called when data readable on stdin */
153\& static void
154\& stdin_cb (EV_P_ struct ev_io *w, int revents)
155\& {
156\& /* puts ("stdin ready"); */
157\& ev_io_stop (EV_A_ w); /* just a syntax example */
158\& ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
159\& }
160.Ve
161.PP
162.Vb 6
163\& static void
164\& timeout_cb (EV_P_ struct ev_timer *w, int revents)
165\& {
166\& /* puts ("timeout"); */
167\& ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
168\& }
169.Ve
170.PP
171.Vb 4
172\& int
173\& main (void)
174\& {
175\& struct ev_loop *loop = ev_default_loop (0);
176.Ve
177.PP
178.Vb 3
179\& /* initialise an io watcher, then start it */
180\& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
181\& ev_io_start (loop, &stdin_watcher);
182.Ve
183.PP
184.Vb 3
185\& /* simple non-repeating 5.5 second timeout */
186\& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
187\& ev_timer_start (loop, &timeout_watcher);
188.Ve
189.PP
190.Vb 2
191\& /* loop till timeout or data ready */
192\& ev_loop (loop, 0);
193.Ve
194.PP
195.Vb 2
196\& return 0;
197\& }
198.Ve
140.SH "DESCRIPTION" 199.SH "DESCRIPTION"
141.IX Header "DESCRIPTION" 200.IX Header "DESCRIPTION"
142Libev is an event loop: you register interest in certain events (such as a 201Libev is an event loop: you register interest in certain events (such as a
143file descriptor being readable or a timeout occuring), and it will manage 202file descriptor being readable or a timeout occuring), and it will manage
144these event sources and provide your program with events. 203these event sources and provide your program with events.
… …
151watchers\fR, which are relatively small C structures you initialise with the 210watchers\fR, which are relatively small C structures you initialise with the
152details of the event, and then hand it over to libev by \fIstarting\fR the 211details of the event, and then hand it over to libev by \fIstarting\fR the
153watcher. 212watcher.
154.SH "FEATURES" 213.SH "FEATURES"
155.IX Header "FEATURES" 214.IX Header "FEATURES"
156Libev supports select, poll, the linux-specific epoll and the bsd-specific 215Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the linux-specific \f(CW\*(C`epoll\*(C'\fR, the
157kqueue mechanisms for file descriptor events, relative timers, absolute 216bsd-specific \f(CW\*(C`kqueue\*(C'\fR and the solaris-specific event port mechanisms
158timers with customised rescheduling, signal events, process status change 217for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR),
159events (related to \s-1SIGCHLD\s0), and event watchers dealing with the event 218absolute timers with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous
160loop mechanism itself (idle, prepare and check watchers). It also is quite 219signals (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and
161fast (see this benchmark comparing 220event watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR,
162it to libevent for example). 221\&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as
222file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events
223(\f(CW\*(C`ev_fork\*(C'\fR).
224.PP
225It also is quite fast (see this
226benchmark comparing it to libevent
227for example).
163.SH "CONVENTIONS" 228.SH "CONVENTIONS"
164.IX Header "CONVENTIONS" 229.IX Header "CONVENTIONS"
165Libev is very configurable. In this manual the default configuration 230Libev is very configurable. In this manual the default configuration will
166will be described, which supports multiple event loops. For more info 231be described, which supports multiple event loops. For more info about
167about various configuration options please have a look at the file 232various configuration options please have a look at \fB\s-1EMBED\s0\fR section in
168\&\fI\s-1README\s0.embed\fR in the libev distribution. If libev was configured without 233this manual. If libev was configured without support for multiple event
169support for multiple event loops, then all functions taking an initial 234loops, then all functions taking an initial argument of name \f(CW\*(C`loop\*(C'\fR
170argument of name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) 235(which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have this argument.
171will not have this argument.
172.SH "TIME REPRESENTATION" 236.SH "TIME REPRESENTATION"
173.IX Header "TIME REPRESENTATION" 237.IX Header "TIME REPRESENTATION"
174Libev represents time as a single floating point number, representing the 238Libev represents time as a single floating point number, representing the
175(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near 239(fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near
176the beginning of 1970, details are complicated, don't ask). This type is 240the beginning of 1970, details are complicated, don't ask). This type is
… …
201Usually, it's a good idea to terminate if the major versions mismatch, 265Usually, it's a good idea to terminate if the major versions mismatch,
202as this indicates an incompatible change. Minor versions are usually 266as this indicates an incompatible change. Minor versions are usually
203compatible to older versions, so a larger minor version alone is usually 267compatible to older versions, so a larger minor version alone is usually
204not a problem. 268not a problem.
205.Sp 269.Sp
206Example: make sure we haven't accidentally been linked against the wrong 270Example: Make sure we haven't accidentally been linked against the wrong
207version: 271version.
208.Sp 272.Sp
209.Vb 3 273.Vb 3
210\& assert (("libev version mismatch", 274\& assert (("libev version mismatch",
211\& ev_version_major () == EV_VERSION_MAJOR 275\& ev_version_major () == EV_VERSION_MAJOR
212\& && ev_version_minor () >= EV_VERSION_MINOR)); 276\& && ev_version_minor () >= EV_VERSION_MINOR));
… …
252.Sp 316.Sp
253You could override this function in high-availability programs to, say, 317You could override this function in high-availability programs to, say,
254free some memory if it cannot allocate memory, to use a special allocator, 318free some memory if it cannot allocate memory, to use a special allocator,
255or even to sleep a while and retry until some memory is available. 319or even to sleep a while and retry until some memory is available.
256.Sp 320.Sp
257Example: replace the libev allocator with one that waits a bit and then 321Example: Replace the libev allocator with one that waits a bit and then
258retries: better than mine). 322retries).
259.Sp 323.Sp
260.Vb 6 324.Vb 6
261\& static void * 325\& static void *
262\& persistent_realloc (void *ptr, size_t size) 326\& persistent_realloc (void *ptr, size_t size)
263\& { 327\& {
… …
289callback is set, then libev will expect it to remedy the sitution, no 353callback is set, then libev will expect it to remedy the sitution, no
290matter what, when it returns. That is, libev will generally retry the 354matter what, when it returns. That is, libev will generally retry the
291requested operation, or, if the condition doesn't go away, do bad stuff 355requested operation, or, if the condition doesn't go away, do bad stuff
292(such as abort). 356(such as abort).
293.Sp 357.Sp
294Example: do the same thing as libev does internally: 358Example: This is basically the same thing that libev does internally, too.
295.Sp 359.Sp
296.Vb 6 360.Vb 6
297\& static void 361\& static void
298\& fatal_error (const char *msg) 362\& fatal_error (const char *msg)
299\& { 363\& {
… …
448Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is 512Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is
449always distinct from the default loop. Unlike the default loop, it cannot 513always distinct from the default loop. Unlike the default loop, it cannot
450handle signal and child watchers, and attempts to do so will be greeted by 514handle signal and child watchers, and attempts to do so will be greeted by
451undefined behaviour (or a failed assertion if assertions are enabled). 515undefined behaviour (or a failed assertion if assertions are enabled).
452.Sp 516.Sp
453Example: try to create a event loop that uses epoll and nothing else. 517Example: Try to create a event loop that uses epoll and nothing else.
454.Sp 518.Sp
455.Vb 3 519.Vb 3
456\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 520\& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
457\& if (!epoller) 521\& if (!epoller)
458\& fatal ("no epoll found here, maybe it hides under your chair"); 522\& fatal ("no epoll found here, maybe it hides under your chair");
… …
556\& be handled here by queueing them when their watcher gets executed. 620\& be handled here by queueing them when their watcher gets executed.
557\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 621\& - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
558\& were used, return, otherwise continue with step *. 622\& were used, return, otherwise continue with step *.
559.Ve 623.Ve
560.Sp 624.Sp
561Example: queue some jobs and then loop until no events are outsanding 625Example: Queue some jobs and then loop until no events are outsanding
562anymore. 626anymore.
563.Sp 627.Sp
564.Vb 4 628.Vb 4
565\& ... queue jobs here, make sure they register event watchers as long 629\& ... queue jobs here, make sure they register event watchers as long
566\& ... as they still have work to do (even an idle watcher will do..) 630\& ... as they still have work to do (even an idle watcher will do..)
… …
588visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if 652visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting if
589no event watchers registered by it are active. It is also an excellent 653no event watchers registered by it are active. It is also an excellent
590way to do this for generic recurring timers or from within third-party 654way to do this for generic recurring timers or from within third-party
591libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR. 655libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR.
592.Sp 656.Sp
593Example: create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR 657Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR
594running when nothing else is active. 658running when nothing else is active.
595.Sp 659.Sp
596.Vb 4 660.Vb 4
597\& struct dv_signal exitsig; 661\& struct ev_signal exitsig;
598\& ev_signal_init (&exitsig, sig_cb, SIGINT); 662\& ev_signal_init (&exitsig, sig_cb, SIGINT);
599\& ev_signal_start (myloop, &exitsig); 663\& ev_signal_start (loop, &exitsig);
600\& evf_unref (myloop); 664\& evf_unref (loop);
601.Ve 665.Ve
602.Sp 666.Sp
603Example: for some weird reason, unregister the above signal handler again. 667Example: For some weird reason, unregister the above signal handler again.
604.Sp 668.Sp
605.Vb 2 669.Vb 2
606\& ev_ref (myloop); 670\& ev_ref (loop);
607\& ev_signal_stop (myloop, &exitsig); 671\& ev_signal_stop (loop, &exitsig);
608.Ve 672.Ve
609.SH "ANATOMY OF A WATCHER" 673.SH "ANATOMY OF A WATCHER"
610.IX Header "ANATOMY OF A WATCHER" 674.IX Header "ANATOMY OF A WATCHER"
611A watcher is a structure that you create and register to record your 675A watcher is a structure that you create and register to record your
612interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to 676interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to
… …
792Returns a true value iff the watcher is pending, (i.e. it has outstanding 856Returns a true value iff the watcher is pending, (i.e. it has outstanding
793events but its callback has not yet been invoked). As long as a watcher 857events but its callback has not yet been invoked). As long as a watcher
794is pending (but not active) you must not call an init function on it (but 858is pending (but not active) you must not call an init function on it (but
795\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to 859\&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe) and you must make sure the watcher is available to
796libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it). 860libev (e.g. you cnanot \f(CW\*(C`free ()\*(C'\fR it).
797.IP "callback = ev_cb (ev_TYPE *watcher)" 4 861.IP "callback ev_cb (ev_TYPE *watcher)" 4
798.IX Item "callback = ev_cb (ev_TYPE *watcher)" 862.IX Item "callback ev_cb (ev_TYPE *watcher)"
799Returns the callback currently set on the watcher. 863Returns the callback currently set on the watcher.
800.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 864.IP "ev_cb_set (ev_TYPE *watcher, callback)" 4
801.IX Item "ev_cb_set (ev_TYPE *watcher, callback)" 865.IX Item "ev_cb_set (ev_TYPE *watcher, callback)"
802Change the callback. You can change the callback at virtually any time 866Change the callback. You can change the callback at virtually any time
803(modulo threads). 867(modulo threads).
… …
829\& struct my_io *w = (struct my_io *)w_; 893\& struct my_io *w = (struct my_io *)w_;
830\& ... 894\& ...
831\& } 895\& }
832.Ve 896.Ve
833.PP 897.PP
834More interesting and less C\-conformant ways of catsing your callback type 898More interesting and less C\-conformant ways of casting your callback type
835have been omitted.... 899instead have been omitted.
900.PP
901Another common scenario is having some data structure with multiple
902watchers:
903.PP
904.Vb 6
905\& struct my_biggy
906\& {
907\& int some_data;
908\& ev_timer t1;
909\& ev_timer t2;
910\& }
911.Ve
912.PP
913In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more complicated,
914you need to use \f(CW\*(C`offsetof\*(C'\fR:
915.PP
916.Vb 1
917\& #include <stddef.h>
918.Ve
919.PP
920.Vb 6
921\& static void
922\& t1_cb (EV_P_ struct ev_timer *w, int revents)
923\& {
924\& struct my_biggy big = (struct my_biggy *
925\& (((char *)w) - offsetof (struct my_biggy, t1));
926\& }
927.Ve
928.PP
929.Vb 6
930\& static void
931\& t2_cb (EV_P_ struct ev_timer *w, int revents)
932\& {
933\& struct my_biggy big = (struct my_biggy *
934\& (((char *)w) - offsetof (struct my_biggy, t2));
935\& }
936.Ve
836.SH "WATCHER TYPES" 937.SH "WATCHER TYPES"
837.IX Header "WATCHER TYPES" 938.IX Header "WATCHER TYPES"
838This section describes each watcher in detail, but will not repeat 939This section describes each watcher in detail, but will not repeat
839information given in the last section. Any initialisation/set macros, 940information given in the last section. Any initialisation/set macros,
840functions and members specific to the watcher type are explained. 941functions and members specific to the watcher type are explained.
… …
901The file descriptor being watched. 1002The file descriptor being watched.
902.IP "int events [read\-only]" 4 1003.IP "int events [read\-only]" 4
903.IX Item "int events [read-only]" 1004.IX Item "int events [read-only]"
904The events being watched. 1005The events being watched.
905.PP 1006.PP
906Example: call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well 1007Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well
907readable, but only once. Since it is likely line\-buffered, you could 1008readable, but only once. Since it is likely line\-buffered, you could
908attempt to read a whole line in the callback: 1009attempt to read a whole line in the callback.
909.PP 1010.PP
910.Vb 6 1011.Vb 6
911\& static void 1012\& static void
912\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1013\& stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
913\& { 1014\& {
… …
1005.IX Item "ev_tstamp repeat [read-write]" 1106.IX Item "ev_tstamp repeat [read-write]"
1006The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out 1107The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out
1007or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any), 1108or \f(CW\*(C`ev_timer_again\*(C'\fR is called and determines the next timeout (if any),
1008which is also when any modifications are taken into account. 1109which is also when any modifications are taken into account.
1009.PP 1110.PP
1010Example: create a timer that fires after 60 seconds. 1111Example: Create a timer that fires after 60 seconds.
1011.PP 1112.PP
1012.Vb 5 1113.Vb 5
1013\& static void 1114\& static void
1014\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1115\& one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
1015\& { 1116\& {
… …
1021\& struct ev_timer mytimer; 1122\& struct ev_timer mytimer;
1022\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.); 1123\& ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
1023\& ev_timer_start (loop, &mytimer); 1124\& ev_timer_start (loop, &mytimer);
1024.Ve 1125.Ve
1025.PP 1126.PP
1026Example: create a timeout timer that times out after 10 seconds of 1127Example: Create a timeout timer that times out after 10 seconds of
1027inactivity. 1128inactivity.
1028.PP 1129.PP
1029.Vb 5 1130.Vb 5
1030\& static void 1131\& static void
1031\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1132\& timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
… …
1156.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]" 1257.IX Item "ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]"
1157The current reschedule callback, or \f(CW0\fR, if this functionality is 1258The current reschedule callback, or \f(CW0\fR, if this functionality is
1158switched off. Can be changed any time, but changes only take effect when 1259switched off. Can be changed any time, but changes only take effect when
1159the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. 1260the periodic timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called.
1160.PP 1261.PP
1161Example: call a callback every hour, or, more precisely, whenever the 1262Example: Call a callback every hour, or, more precisely, whenever the
1162system clock is divisible by 3600. The callback invocation times have 1263system clock is divisible by 3600. The callback invocation times have
1163potentially a lot of jittering, but good long-term stability. 1264potentially a lot of jittering, but good long-term stability.
1164.PP 1265.PP
1165.Vb 5 1266.Vb 5
1166\& static void 1267\& static void
… …
1174\& struct ev_periodic hourly_tick; 1275\& struct ev_periodic hourly_tick;
1175\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); 1276\& ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
1176\& ev_periodic_start (loop, &hourly_tick); 1277\& ev_periodic_start (loop, &hourly_tick);
1177.Ve 1278.Ve
1178.PP 1279.PP
1179Example: the same as above, but use a reschedule callback to do it: 1280Example: The same as above, but use a reschedule callback to do it:
1180.PP 1281.PP
1181.Vb 1 1282.Vb 1
1182\& #include <math.h> 1283\& #include <math.h>
1183.Ve 1284.Ve
1184.PP 1285.PP
… …
1192.PP 1293.PP
1193.Vb 1 1294.Vb 1
1194\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1295\& ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1195.Ve 1296.Ve
1196.PP 1297.PP
1197Example: call a callback every hour, starting now: 1298Example: Call a callback every hour, starting now:
1198.PP 1299.PP
1199.Vb 4 1300.Vb 4
1200\& struct ev_periodic hourly_tick; 1301\& struct ev_periodic hourly_tick;
1201\& ev_periodic_init (&hourly_tick, clock_cb, 1302\& ev_periodic_init (&hourly_tick, clock_cb,
1202\& fmod (ev_now (loop), 3600.), 3600., 0); 1303\& fmod (ev_now (loop), 3600.), 3600., 0);
… …
1253.IP "int rstatus [read\-write]" 4 1354.IP "int rstatus [read\-write]" 4
1254.IX Item "int rstatus [read-write]" 1355.IX Item "int rstatus [read-write]"
1255The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems 1356The process exit/trace status caused by \f(CW\*(C`rpid\*(C'\fR (see your systems
1256\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details). 1357\&\f(CW\*(C`waitpid\*(C'\fR and \f(CW\*(C`sys/wait.h\*(C'\fR documentation for details).
1257.PP 1358.PP
1258Example: try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0. 1359Example: Try to exit cleanly on \s-1SIGINT\s0 and \s-1SIGTERM\s0.
1259.PP 1360.PP
1260.Vb 5 1361.Vb 5
1261\& static void 1362\& static void
1262\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1363\& sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1263\& { 1364\& {
… …
1282not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is 1383not exist\*(R" is signified by the \f(CW\*(C`st_nlink\*(C'\fR field being zero (which is
1283otherwise always forced to be at least one) and all the other fields of 1384otherwise always forced to be at least one) and all the other fields of
1284the stat buffer having unspecified contents. 1385the stat buffer having unspecified contents.
1285.PP 1386.PP
1286Since there is no standard to do this, the portable implementation simply 1387Since there is no standard to do this, the portable implementation simply
1287calls \f(CW\*(C`stat (2)\*(C'\fR regulalry on the path to see if it changed somehow. You 1388calls \f(CW\*(C`stat (2)\*(C'\fR regularly on the path to see if it changed somehow. You
1288can specify a recommended polling interval for this case. If you specify 1389can specify a recommended polling interval for this case. If you specify
1289a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable, 1390a polling interval of \f(CW0\fR (highly recommended!) then a \fIsuitable,
1290unspecified default\fR value will be used (which you can expect to be around 1391unspecified default\fR value will be used (which you can expect to be around
1291five seconds, although this might change dynamically). Libev will also 1392five seconds, although this might change dynamically). Libev will also
1292impose a minimum interval which is currently around \f(CW0.1\fR, but thats 1393impose a minimum interval which is currently around \f(CW0.1\fR, but thats
… …
1294.PP 1395.PP
1295This watcher type is not meant for massive numbers of stat watchers, 1396This watcher type is not meant for massive numbers of stat watchers,
1296as even with OS-supported change notifications, this can be 1397as even with OS-supported change notifications, this can be
1297resource\-intensive. 1398resource\-intensive.
1298.PP 1399.PP
1299At the time of this writing, no specific \s-1OS\s0 backends are implemented, but 1400At the time of this writing, only the Linux inotify interface is
1300if demand increases, at least a kqueue and inotify backend will be added. 1401implemented (implementing kqueue support is left as an exercise for the
1402reader). Inotify will be used to give hints only and should not change the
1403semantics of \f(CW\*(C`ev_stat\*(C'\fR watchers, which means that libev sometimes needs
1404to fall back to regular polling again even with inotify, but changes are
1405usually detected immediately, and if the file exists there will be no
1406polling.
1301.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4 1407.IP "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 4
1302.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)" 1408.IX Item "ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)"
1303.PD 0 1409.PD 0
1304.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4 1410.IP "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 4
1305.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)" 1411.IX Item "ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)"
… …
1387.IX Item "ev_idle_init (ev_signal *, callback)" 1493.IX Item "ev_idle_init (ev_signal *, callback)"
1388Initialises and configures the idle watcher \- it has no parameters of any 1494Initialises and configures the idle watcher \- it has no parameters of any
1389kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, 1495kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless,
1390believe me. 1496believe me.
1391.PP 1497.PP
1392Example: dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR, start it, and in the 1498Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the
1393callback, free it. Alos, use no error checking, as usual. 1499callback, free it. Also, use no error checking, as usual.
1394.PP 1500.PP
1395.Vb 7 1501.Vb 7
1396\& static void 1502\& static void
1397\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1503\& idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1398\& { 1504\& {
… …
2069otherwise another method will be used as fallback. This is the preferred 2175otherwise another method will be used as fallback. This is the preferred
2070backend for Solaris 10 systems. 2176backend for Solaris 10 systems.
2071.IP "\s-1EV_USE_DEVPOLL\s0" 4 2177.IP "\s-1EV_USE_DEVPOLL\s0" 4
2072.IX Item "EV_USE_DEVPOLL" 2178.IX Item "EV_USE_DEVPOLL"
2073reserved for future expansion, works like the \s-1USE\s0 symbols above. 2179reserved for future expansion, works like the \s-1USE\s0 symbols above.
2180.IP "\s-1EV_USE_INOTIFY\s0" 4
2181.IX Item "EV_USE_INOTIFY"
2182If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify
2183interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will
2184be detected at runtime.
2074.IP "\s-1EV_H\s0" 4 2185.IP "\s-1EV_H\s0" 4
2075.IX Item "EV_H" 2186.IX Item "EV_H"
2076The name of the \fIev.h\fR header file used to include it. The default if 2187The name of the \fIev.h\fR header file used to include it. The default if
2077undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This 2188undefined is \f(CW\*(C`<ev.h>\*(C'\fR in \fIevent.h\fR and \f(CW"ev.h"\fR in \fIev.c\fR. This
2078can be used to virtually rename the \fIev.h\fR header file in case of conflicts. 2189can be used to virtually rename the \fIev.h\fR header file in case of conflicts.
… …
2123.IP "\s-1EV_PID_HASHSIZE\s0" 4 2234.IP "\s-1EV_PID_HASHSIZE\s0" 4
2124.IX Item "EV_PID_HASHSIZE" 2235.IX Item "EV_PID_HASHSIZE"
2125\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by 2236\&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by
2126pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more 2237pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more
2127than enough. If you need to manage thousands of children you might want to 2238than enough. If you need to manage thousands of children you might want to
2128increase this value. 2239increase this value (\fImust\fR be a power of two).
2240.IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4
2241.IX Item "EV_INOTIFY_HASHSIZE"
2242\&\f(CW\*(C`ev_staz\*(C'\fR watchers use a small hash table to distribute workload by
2243inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR),
2244usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR
2245watchers you might want to increase this value (\fImust\fR be a power of
2246two).
2129.IP "\s-1EV_COMMON\s0" 4 2247.IP "\s-1EV_COMMON\s0" 4
2130.IX Item "EV_COMMON" 2248.IX Item "EV_COMMON"
2131By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining 2249By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining
2132this macro to a something else you can include more and other types of 2250this macro to a something else you can include more and other types of
2133members. You have to define it each time you include one of the files, 2251members. You have to define it each time you include one of the files,
… …
2197.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)" 2315.IX Item "Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)"
2198.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4 2316.IP "Starting io/check/prepare/idle/signal/child watchers: O(1)" 4
2199.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)" 2317.IX Item "Starting io/check/prepare/idle/signal/child watchers: O(1)"
2200.IP "Stopping check/prepare/idle watchers: O(1)" 4 2318.IP "Stopping check/prepare/idle watchers: O(1)" 4
2201.IX Item "Stopping check/prepare/idle watchers: O(1)" 2319.IX Item "Stopping check/prepare/idle watchers: O(1)"
2202.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 4 2320.IP "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % \s-1EV_PID_HASHSIZE\s0))" 4
2203.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))" 2321.IX Item "Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))"
2204.IP "Finding the next timer per loop iteration: O(1)" 4 2322.IP "Finding the next timer per loop iteration: O(1)" 4
2205.IX Item "Finding the next timer per loop iteration: O(1)" 2323.IX Item "Finding the next timer per loop iteration: O(1)"
2206.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4 2324.IP "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 4
2207.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)" 2325.IX Item "Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)"
2208.IP "Activating one watcher: O(1)" 4 2326.IP "Activating one watcher: O(1)" 4

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